Secondary phase strengthened high coercivity in sputtered D022 Mn3−xGa films

Abstract Rare-earth-free permanent magnet Mn-Ga alloys have attracted wide interest owing to their large magnetocrystalline anisotropy and high Curie temperature. In this work, we reported a large coercivity of ~22 kOe at room temperature in the Mn3−xGa film, deposited by magnetron sputtering on the Si(0 0 1)/SiO2 substrate. Combined analyses of the x-ray diffraction, magnetization and high-resolution transmission electron microscopy revealed a cubic α-Mn phase coexisting with the main D022 ferrimagnetic phase in the film. It is proved that the mixed structures can refine the magnetic domains, thus enhancing the coercivity in the high temperature annealed sample.